Introducing Extreme Lost Circulation Materials and Application of such Materials in V

Introducing Extreme Lost Circulation Materials andApplication of such Materials in Varavi Gas Field ofNICOFC...--- Lost circulation or lost return is defined as the partial or total loss of whole drillingfluid to subsurface formations. Probably the most problematic situation is naturallyfractured formations where the operator may face total loss with no mud return inthe annular.The voids or large fractures encountered in this case are often too large to beplugged with conventional Lost Circulation Materials (LCM). Hence, massive lostcirculation is a major and costly drilling problem.New approaches to cure extreme losses are “settable plugs”. This term is used forslurries which gel or solidify in seal zones. When these fluids are being lost to theformation they should gel quickly as it travels away from the wellbore, as the fluidvelocity decreases. Some examples of such plugging products are gunks or crosslinkedpolymers.The objective of this paper is to explain extreme lost circulation problem andintroduce different solutions in addition to recently developed materials to cure ormitigate this problem. And finally, the application of a polymer based wellplug isstudied in one well of the Varavi Gas Field (National Iranian Central Oil FieldCompany) and the reasons of unsuccessful trial of this material with regard to futurerecommendations are examined.